The shell of the abalone is exceptionally strong and is made of microscopic calcium carbonate tiles stacked like bricks. Between the layers of shells is a clingy protein substance. When the abalone shell is struck, the tiles slide instead of shattering and the protein stretches to absorb the energy of the blow. Material scientists around the world are studying the tiled structure for insight into stronger ceramic products.

The color of the shell is very variable from species to species, and may reflect diet. The iridescent nacre that lines the inside of the shell varies in color from silvery white, to pink, red and green-red, through to Haliotis iris, which shows predominantly deep blues, greens and purples.

There is only the one genus in the family Haliotidae, and about four to seven subgenera. The number of species recognized worldwide is about 100.